Pupils nickname him BFG, after the Roald Dahl character, or Shrek, another gentle giant.
Alan Stern is the six-foot-plus Eaglesham Primary janitor, who coaches them in athletics, football, rugby and cycling proficiency, and who leads the eco-school activities.
But he was named "Educational Supporter of the Year" in this year's Scottish Education Awards, because he is much, much more.
Diagnosed profoundly deaf at the age of four, Mr Stern, 47, never allows his disability to get in the way of the job he has held at the East Renfrewshire primary for the past 19 years. More significantly, he is living proof to pupils of what a disabled person can achieve, shaping their attitudes to inclusion.
Born and brought up in the southside of Glasgow, he reflects on how differently children with additional needs are supported in mainstream education nowadays, compared with his childhood. He was bullied a lot at school "because I was deaf and I was different"; he would get angry and frustrated and "lash out" at others.
"In those days it was a struggle because they didn't know a lot about deafness. I got help with speech lessons but, when I left King's Park Secondary at 16, I didn't get help from the deaf community because my parents were hearing," he says.
He taught himself to lip-read, but no one prepared him for the jobs he could and couldn't do.
Jobs after school included training as a chef under the Youth Opportunities Scheme, working as a bouncer and helping to build the airport on the Falkland Islands. Then, in 1991, he got a job as a janitor at Shawlands Academy in Glasgow and moved the following year to Eaglesham Primary.
"In this job, I can do all these sports and activities and have all the fun in the world. I wouldn't change it," he says.
That is a typical understatement of his relationship with staff at Eaglesham Primary.
Head Linda Congalton says: "Nothing is too much trouble. He carries teachers' bags and boxes, he puts up wall displays, he will change tyres, dig us out of snow and even drive us to our door in a snowstorm."
He even checks her eye make-up in the morning, mouthing "mascara" if it has smudged on her drive into work, she reveals.
Mr Stern's prowess as a sports coach is renowned in the village: he coaches P4-7 boys and girls in football at lunchtimes and after school; coaches rugby with P5-7; and takes a running club for P4-7 in rain, hail or snow, encouraging children to take part in cross-country championships. British Schools cross-country champion Jack Walker, now 16, attributes his athletic success to Mr Stern's initial training and discipline.
With a pupil support assistant, he trains P6-7 children in cycling proficiency, with a 100 per cent pass rate. He accompanies the children to Aviemore for their annual skiing trip (and, not to be beaten, is learning to ski himself) and helps out at the P7 annual outdoor education week at Ardentinny.
At weekends, he comes into school to ensure the trout being reared as part of the Cart River project are still alive - last year, the school released 250 fish back into the river, possibly a record.
And he is an integral part of school charity events, dressing up variously as Simon Cowell, a naughty school boy and Braveheart.
"When I was at school, I missed out on a lot of things - sports were my release. It's good to have the kids out, letting off steam at lunchtime. When they get back, they feel better," he says.
He'd like to have been a PE teacher but didn't realise he could have got support at college, so didn't attempt it. But he finds real fulfilment in his many roles at Eaglesham.
"I'm a team player - that's why I get on with the staff. I do all these activities for the children. I enjoy working with them. I'm hard but fair," he says.
The children know they have to face him when they are speaking to him and that they have to speak clearly. "But they cheek me just the same as the others," he jokes.
He is not averse to using humour himself and is renowned as a practical joker. Just ask Samantha Oattes, who works in the school office, about the time he clingfilmed over everything on her desk, including the computer.
But for all his ebullience, there's a very perceptive side to Mr Stern, as Mrs Congalton observes. "He's very good at identifying the loners and drawing these children in and giving them a purpose. Before you know it, they are part of the group and their self-esteem has shot through the roof. He's on a mission to ensure that no other child has a school life like his," she says.
Outside school, Mr Stern is vice-chairman of the West Scotland Deaf Children's Society. He is also married with two children, Mr Stern's 16- year-old son Fraser has inherited his deafness. Fraser attends Mearns Castle High and is in a mainstream class. "He sees me and knows that, with a bit of help, things can be achieved. But sometimes you need help from other people."